Aluminum coatings based on clay-emulsified asphalts

ABSTRACT

An aluminum-clay base asphalt emulsion having a major amount of the clay base asphalt emulsion and a minor amount of an aluminum paste is found to give good reflective properties and spread smoothly.

Unite States Patent 1191 {111 3,869,297

Bellamy 1 Mar. 4, 1975 ALUMINUM COATINGS BASED ON 2,353,723 7/1944 Groskopf 106/277 x CLAYJBMULSIFHED ASPHALTS 2,477,236 7/1949 Buchanan 106/282 2,620,312 12/1952 Manzer 106/277 X Inventor: RobertC-Be1l9my,Balt1m0re,Md- 3,027,342 3/1962 Kemp et a1 106/277 ux 3,244,542 4/1966 Brown et a1. 106/277 [73] Assgnee' 9 i Company San 3,296,165 l/l967 Kemp 106/277 x mascot 3,394,550 7/1968 Ferm 106/277 x [22] Filed: June 5 970 3,493,408 2/1970 Drukker 106/277 [21] Appl' 46518 Primary Examiner-Joan E. Welcome Attorney, Agent, or Firm-G. F. Magdeburger; C. .1. [52] US. Cl 106/277, 106/281, 106/283, Tonkin; B. G. Fehringer 252/311.5 [51] Int. Cl...... C08h 13/00, C08k l/62, C09d 3/24 B TR [58] Field of Search 106/277-284; [57] A S ACT 94/1943; 252/311 5 An alumlnum-clay base asphalt emulslon having a major amount of the clay base asphalt emulsion and a 5 References Cited minor amount of an aluminum paste is found to give UNITED STATES PATENTS good reflective properties and spread smoothly.

1,765,676 6/1930 Jones 106/277 6 Claims, N0 Drawings ALUMINUM COATINGS BASED ON CLAY-EMULSIFIED ASPHALTS BACKGROUND OF THE INVENTION 1. Field of the Invention Aluminum asbestos coatings have been on the market for many years and their excellent weathering, water-proofing, and heat reflective properties have made them a standard throughout the roofing industry. The chief benefits of these coatings lie in their reflective nature. Since a large percentage of the suns rays are reflected as opposed to being absorbed, the coating remains at a lower temperature and maintains the adjoin-.

ing interior areas of the structures at substantially lower temperatures. Interior temperatures as much as 15 25F below ambient exterior temperatures can be obtained as a direct result of the use of these aluminum coatings. When properly applied, coatings may have a useful life of years.

Aluminum asbestos coatings consist of a thin asphalt cut-back base material, asbestos, non-fibrous fillers such as mica, and a leafing grade of aluminum pigment. It is the aluminum pigment and the phenomenon known as leafing" which makes this coating attractive and long-lasting. Leafing is defined as the action by which aluminum flakes concentrate at the surface of a coating and orient themselves with their flat dimension parallel to it. If sufficient aluminum pigment is present in a coating, the flakes overlap one another and form what appears to be a continuous metallic film. This multiple-tiered sheath of aluminum, when properly formed, is effective to reflect 70 percent or more of the suns radiant energy and greatly reduces the actinic deterioration of the asphalt binder.

Although aluminum asbestos coatings are widely accepted and used, they do suffer from certain deficiencies, both from the application and technical standpoint. The product is difficult to apply because of its vulnerability to asphalt bleed-through which results in an unsightly brown discoloration of the applied coating. This bleed-through can occur within a few days of the application or anytime up to about 2 months. Further, aluminum asbestos coatings cannot be applied to fresh unweathered asphalt and asphalt base coatings. If priming is required on an old worn surface, the priming asphalt must be allowed to weather before final application of the aluminum asbestos coating can be made. The result of this characteristic of aluminum asbestos coatings is that at least two separate trips to a job site must be made before a particular job can be completed. Further, heavy applications of coatings are difficult to prevent since they can occur by uneven application by brush or uneven spraying or spray overlap and, in addition, these excessively heavy application of coatings are very susceptible to bleed-through and can give an uneven coloration even if bleed-through does not occur.

Manufacturing and packaging of aluminum asbestos coatings often present problems. Formulations are complex and selection of the proper starting materials (particularly solvents) is critical. Further, order and method of mixing in order to obtain maximum leafing and brightness is of extreme importance. The product is composed of 50 percent or more, by volume, of solvents and presents a fire hazard.

Also, certain local air pollution control boards, such as in Los Angeles County and the San Franciso area, impose regulations regarding solvent emission and composition which in effect limit the field of exempt solvents which can be used in formulating the aluminum asbestos coating materials. The use of these exempt solvents can affect the leafing action of the aluminum flakes and reduce the overall performance of the coating.

Moisture entering the system during manufacturing of the coating materials causes problems. When water contamination as low as 0.15 percent occurs, bronzing of the coating in storage very quickly renders the material useless. In higher quantities, water contamination causes gassing of the compositions (hydrogen gas forms by reaction of the aluminum with the water) and results in a safety hazard. It is clear that, if a suitable composition could be obtained which would have the outstanding weatherability and coating characteristics of the aluminum asbestos coating compositions but be free of the deficiencies set forth above, a valuable contribution to the roofing industry would be made.

The subject invention then is directed toward an aluminum coating composition which has the desirable features of the aluminum-asbestos coating discussed above without the concomitant drawbacks.

2. Description of the Prior Art US. Pat. No. 1,765,676 describes a protective coating for use as a paint covering on metal, concretes, cement and similar surfaces. The coating is described as any water, alcohol or similar emulsions, such as asphalt or other bituminous material, into which is incorporated a powdered or finely divided metal, such as powdered metallic aluminum. A specific example set forth in reference teaches making an asphalt emulsion of from 50 to percent of asphalt with soap or clay used as the emulsifying agent. When clay is used, not more than 10 percent is taught as suffioient. To this emulsion is added from 3 to 10 percent by weight of aluminum powder which was first mixed with water and stirred.

US. Pat. No. 3,244,542 discloses a paste formation in which aluminum metallic pigmentation has been treated to provide surfaces of the individual flakes thereof with a protective cell to prohibit corrosive attack of the metallic pigmentations by water. It is stated therein that it is a well-known fact that metallic pigments, particularly aluminum flake pigments, are seriously affected on contact with exposure to even trace quantities of water in sealed containers, with the effect of the water being most notably observed in the development of gas pressure within seal containers of the formulations, and accompanied by a loss of luster, gloss, brilliance and natural color of the metallic flake component. The reference also discloses the use of leafing aluminum flake powder in a bituminous tar emulsion type vehicle.

SUMMARY OF THE INVENTION An aluminum-clay base asphalt emulsion system is obtained by mixing (l a major amount of a clay base asphalt emulsion and (2) a minor amount of an aluminum paste and blending until the resulting composition is smooth. The clay base asphalt emulsion contains (1) asphalt, (2) clay, and (3) water and preferably contains (1) a mixing stability additive, (2) metasilicic acid, and (3) ferric chloride hydrate. The aluminum paste is made up of aluminum flake pigment of leafing grade coated with a protective film to inhibit corrosive attack by water. The blending operation may optionally incorporate additional water and additional mixing stability additive into the system together with mica and sodium citrate.

The composition is useful as a coating material for roofing systems where high reflectivity of the suns radiation is desired.

DESCRIPTION OF THE INVENTION Coating Compositions The coating compositions of this invention comprise (l) a clay base asphalt emulsion mixed with (2) an aluminum paste. The clay base asphalt emulsion preferably contains (1) a mixing stability additive, (2) metasilicic acid, and (3) ferric chloride hydrate. Additional water and additional mixing stability additive, together with sodium citrate and mica, may also be introduced into the system during blending of the emulsion and the aluminum paste. All parts hereafter are by weight.

Formulations of this invention comprise about 750 parts by weight of the clay base asphalt emulsion, from about 50 to 250 parts aluminum paste, from about to 2.5 parts mixing stability additive, from about 0 to 250 parts mica, from 0 to 250 parts additional water added during mixing and blending, and from 0 to about 5 parts sodium citrate hydrate.

A preferred composition is where the clay base asphalt emulsion is present in an amount of about 750 parts, the aluminum paste is present in an amount of from about 100 to 200 parts, the mixing stability additivc is present in an amount of from about 0.5 to about 2.0 parts, mica is present in an amount of from about 50 to 150 parts, the additional water is present in an amount of from about 150 to about 250 parts, and the sodium citrate hydrate is present in an amount of from about 0.5 to about 1.5 parts.

A particularly preferred composition is where the clay base asphalt emulsion is present in an amount of about 750 parts, the aluminum paste is present in an amount of from about 125 to about 175 parts, the mixing stability additive is present in an amount of from about 1 to about 1.5 parts, mica is present in an amount of from about 75 to 125 parts, additional water is present in an amount of from about 150 to 250 parts, and the sodium citrate hydrate is present in an amount of from about 0.5 to about 1.0 part.

A specific preferred composition is comprised of 750 parts clay emulsion, 150 parts aluminum paste, about 1 to 1.5 parts barium chloride hydrate, 100 parts of mica of 100 mesh grade, about 150 to 250 parts additional water, and about 0.5 to 1.0 part sodium citrate.

The coating compositions can also be described in terms of the ratio of clay emulsion solids, (the nonvolatile material in the clay base asphalt emulsion) to aluminum metal content. The ratio should be in the range of about 1.5 to 8.0 parts of the clay emulsion solids to 1.0 part of aluminum metal and optimally in the range of about 4.0 to 2.0 parts clay emulsion solids to 1.0 part of aluminum metal.

Compliance with both (1) the ratio criterion set forth, based on emulsions solids and aluminum metal, and (2) the proportions set forth based on the total emulsion content and the aluminum paste are important to obtain a satisfactory coating.

Aluminum Pigment The aluminum paste which is mixed with the clay base asphalt emulsion is comprised of aluminum metallic pigment in the form of flakes which have been treated with a conventional fatty acid lubricating agent and an inhibitor to prevent reaction of the aluminum with the water. Inhibitors are known in the prior art and include compounds such as 3- and 5-nitrosalicyelic acids. Aluminum pastes suitable for this invention include those described in U.S. Pat. No. 3,244,542.. Clay Emulsions The clay base asphalt emulsions used in the subject invention have a non-volatile residue (defined as the parts by weight left after distillation of volatiles based on an initial system of parts by weight using ASTM D-10l0-66) offrom 30 to 55, preferably from 38 to 47, and a clay/asphalt ratio of from about 0.05 0.40:1, preferably from about 0.05 0.10:1 based on weight.

The clay base asphalt emulsions preferably contain minor amounts of metasilicic acid, hydrated ferric chloride, and a mixing stability additive. For example, metasilicic acid may be present in an amount from 0 to about 0.4 part, the hydrated ferric chloride may be present in an amount from 0 to about 0.1 part by weight, and the mixing stability additive, preferably barium chloride hydrate, may be present in an amount from 0 to about 0.2 part by weight.

The clays used in this invention are of the type described in U.S. Pat. No. 2,782,169 and the general method of preparation disclosed therein for preparing clay base asphalt emulsions may be employed in preparing the clay base asphalt emulsions of this invention. Particularly preferred clays are the bentonite clays.

The clay base asphalt emulsions have a mean asphalt particle size (length of long axis of the particles) of from 4 to about 100 microns and, preferably, from about 8 to about 20 microns.

Asphalts Suitable clay base asphalt emulsions can be prepared from asphalts having a penetration of 0 to as high as 250 at 77F. (ASTM D-5) and a softening point in the range of from about 80 to about 300F. (ASTM D-36). The end use of the coating composition dictates the type or grade of asphalt to be used.

For coating compositions which will be used as protective coating and which will be subjected to outdoor environmental conditions, the asphalt used should have a penetration in the range of from about 40 to and a softening point in the range of from 100 to about F. If too soft an asphalt is used (high penetration and low softening point), a coating made from it will be too soft and will tend to flow or run during hot weather. If too hard an asphalt is used (low penetration and high softening point), the coating will be hard and brittle.

A particularly preferred grade of asphalt for use in the preparation of the clay emulsions of this invention is an 85/ 1 00 penetration grade which has the properties set forth in Table I below.

A specific asphalt meeting these properties is an 85/100 penetration grade Boscan asphalt which has the properties set forth in Table II, below.

Mica Filler All grades of mica readily available (40 to 325 mesh) can be used in this invention as fillers. Particularly preferred is the 100 mesh grade.

Mixing Stability Additive The mixing stability additives used in this invention are generally referred to as flocculants in clay emulsion technology. While optional, they serve, when used, to precipitate soluble sulfates which are present in bentonite clays and aid in the dispersion of the aluminum pigment in the clay emulsion to obtain a smooth, nongrainy coating composition (mixing stability). They may be incorporated in the clay base asphalt emulsion itself and may also be used when preparing the aluminum asphalt clay coating composition of this invention as will be pointed out infra. The additives found to be effective in improving mixing stability of the emulsions are barium chloride hydrate, ferric chloride hydrate, stannic chloride hydrate, and stannous chloride hydrate. The barium chloride hydrate is particularly effective. Mixtures of the additives can also be used. As, for example, the clay emulsion can be prepared using stannous chloride hydrate as the primary flocculant with a smaller amount of barium chloride hydrate presem, and additional barium chloride hydrate may be added at the time the aluminum paste is incorporated into the system.

While it has not been possible to quantitatively relate in a single expression the variables affecting the mixing stability of the clay emulsions, i.e., their ability to disperse the aluminum pigment smoothly, certain features of the clay emulsions which have good mixing stability have been determined. These features for a given clay base asphalt emulsion are:

I. For a given residue, the smaller the mean particle size of the clay particles in the emulsion, the more likely it will have mixing stability.

2. For a given residue, the greater the clay to asphalt ratio, the more likely it will have mixing stability.

Clay emulsions having the properties specified under the heading Clay Emulsions, supra, have satisfactory mixing stability.

Metasilicic Acid Metasilicic acid is also optional but serves, when present, to thin down or lower the viscosity of the clay slurry making it easier to handle.

Sodium Citrate Sodium citrate, while optional, acts to (l reduce the viscosity of the product when first manufactured, and (2) reduces the tendency to thicken in storage. Preparation of the Coating Compositions The coating compositions of this invention can be prepared by several methods. The preferred method is carried out by placing in a mixer, such as a Hobart planetary mixer, the formula amount of clay emulsion, adding the specified amount of mixing stability additive and about half of additional water to be added, mixing this combination until homogeneous, followed by adding any filler and mixing. This is followed by adding about one-quarter of the required aluminum paste and mixing at a low speed until thoroughly dispersed, followed by the remainder of the aluminum paste, onequarter at a time, with mixing. The remainder of the additional water is then added with mixing. If sodium citrate is to be used, it is added after the addition as a 10 percent by weight solution in water until the desired viscosity is obtained.

Other methods used in the preparation of coating compositions are as follows:

Method A 1. Add formula amount of Clay Emulsion to mixer.

2. Add 50 percent of formula amount of water and all additives and fillers, and mix.

3. Add aluminum paste, A at a time, and mix until thoroughly dispersed.

4. Add remainder of water. Thin with additional water if required.

Method B 1. Add full amounts of aluminum paste, water, fillers and additives to mixer and mix a smooth slurry.

2. Slowly add formula amount of Clay Emulsion to aluminum slurry.

3. Add extra water if required.

Method C 1. Add full amount of Clay Emulsion, additives and fillers to mixer.

2. In a separate mixer, prepare an aluminum slurry using the formula amounts of aluminum paste and water.

3. Slowly add aluminum slurry to Clay Emulsion.

4. Thin with extra water, if required.

Method A-M, or B-M 1. Prepare sample as per Method A or B. If sample breaks (becomes stiff, balls up in mixer) add additional barium chloride hydrate as 10 percent solution to mixture.

In the following examples which are offered by way of illustration and should not be considered limiting, all parts are by weight unless otherwise specified:

EXAMPLES l 4 This example shows the inoperability of asbestos as a filler in the system.

parts of a clay emulsion having the composition set forth in footnote 1 of Table IV was mixed with 2.5 parts of asbestos fibers, 15 parts of an aluminum paste (Hydro Paste 830, a product of Alcoa), 17.5 parts water, and 0.1125 parts of barium chloride hydrate using Method B.

The product obtained was very grainy, stiff, and gummy, and could not be brushed.

Similar compositions were prepared using the same clay emulsion with the results shown in Table lll.

TABLE 111- Material Example 2 Example 3 Example 4 Clay Emulsion 75.0 75.0 75.0 Asbestos 2.5 2.5 2.5 Hydro Paste 830 15.0 15.0 15.0 Water 15.0 15.0 20.0 Barium Chloride Hydrate 0.1500 0.1125 0.1 125 Mixing Method B A A Uniformity & Texture Very grainy. stiff. Slightly grainy gummy. Could not be and gummy. Very brushed. hard to brush.

EXAMPLES 5 13 weathering stations located at Mobile, Alabama, and

Tracy, California. Similar procedure to that of Examples 1 -4 were fol- 15 Two panels of each of the compositions were prelowed, using mica as the filler with the results shown in pared for each location: One was brush-applied, the

,T bl IV, other was applied with a spatula.

TABLE IV Parts by Weight Material Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13

Clay Emulsion 75.0 75.0 75.0 75.0 75.0 75.0 Clay Emulsion 75.0 75.0 75.0 Hydro Paste 830 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 Miea (250 mesh) 5.0 10.0 15.0 20.0 Mica (100 mesh) 10.0 10.0 Mica (325 mesh) 10.0 15.0 20.0 Barium Chloride 0.1125 0.1125 0.1125 0.1125 0.1125 0.1125 0.1125 0.1125 0.1125

Hydrate Water 12.5 20.5 22.5 25.0 20.0 17.5 22.5 25.0 32.5 Mixing Method B B B B B A B B B Uniformity & Smooth, good brushing. Slightly Grainy. Very smooth. buttery. Texture grainy. Good brushing.

brushing good.

44.335 parts asphalt. 3.5 parts clay. 0.l part barium chloride hydrate; 0025 part metasilicic acid. 004 parts ferric chloride hydrate. and 52 parts water. -'4-l.()25 parts asphalt. 375 parts clay. 0.1 part barium chloride hydrate. 0.025 part metasilicic acid. 0.05 part ferric chloride hydrate. and 52 parts water.

EXAMPLES 14 l7 7 After nine months exposure, the panels were evalu- This example shows the inoperability of limestone as ated visually for physical appearance and color with the a filler in the ys m H V, y V 7 resyltis t ln .b 9w. in.. Tab ey TABLE V1 Weathering results on samples containing asbestos showed a tendency to form surface checking and alligatoring. Ex. 1 -t Asbestos Fibers Most had good color but the checking and alligatoring.

Filler together with the stiff and gummy nature of the product.

which was difficult to apply. initially rendered them completely unsuitable. Weathering results on these samples show mica to be a very good extender pigment for the system. All of these Ex. 5 l3 Mica Filler coatings appeared attractive in quality and appearance.

with no weathering or alligatoring. All grades of mica gave very attractive. satin. silver-white aluminum color. Ex. 14 17 Calcium Carbonate Coatings containing calcium carbonate gave a dull. silver- Filler grey color, instead of a bright. sil er-white color as desired. The amount of calcium carbonate had no appreciable effect on the end color of the applied coatings.

Procedure similar to that used in the previous exam- EXAMPLE 18 ples was followed, using limestone as the filler with the 55 U i M thod A as outlined above, 75 parts by results S ablfi V weight of a clay ernulsion having the formula set forth TABLE v Material: Parts by Wt. Ex. 14 Ex. 15 Ex. 16 Ex. 17

Clay Emulsion 75.0 75.0 75.0 75.0 Hydro Paste 830 15.0 15.0 15.0 15.0 Limestone (200 mesh) 5.35 10.7 16.1 21.4 I Barium Chloride Hydrate 0.1125 0.1125 0.1125 0.1125 Water 15.0 15.0 20.0 22.5 Mixing Method B B B B Uniformity & Texture Smooth good brushing properties Weathering panels of each of the compositions of the in Table V11 below was combined with 9.91 parts by previous 17 examples were prepared and placed at weightof water, 0.l l par t by weightotibaqun chloride completely unsuitable as a coating composition.

TABLE VII Asphalt 85/100 Boscan 44.335 Clay 3.500 Barium chloride hydrate 0.100 Metasilicic acid 0.025 Ferric chloride hydrate 0.040 Water 52.000

In a similar manner using the same clay emulsion a number of other additives were tested for their ability to give a smooth, non-grainy coating'composition with the results shown in Table VIII.

TABLE Vlll very grainy composition. 0.05 weight percent of barium chloride was then added with mixing resulting in a smooth brushing composition.

EXAMPLE 3 i1 75 parts of the same clay emulsion as that of Table VII above (except that the metasilicic acid was deleted) was combined with parts of Hydro Paste 830, 9.9 parts of water, and 0.1 1 part of barium chloride hydrate using Method A. The composition was heavy and very grainy. Six percent by weight of additional water was added and after mixing the composition smoothed out and was easily brushed.

The same composition was again prepared using Method B as outlined above and again a heavy and very grainy composition was obtained. The addition of 4 percent by weight of additional water and mixing resulted in a smooth composition which was easily Results of Use of Additives to Improve Mixing Stability of Clay Emulsion for Use In Aluminum Clay Emulsion Amount Mixing Example Additive Used of CE. Method Results 19 Nonyl phenoxy polyoxy- 0.2

ethylene ethanol 20 NzoSiO, 0.2 A Broke, very grainy 21 Socal 0.2 A Broke. complete coalescence of clay emulsion 22 Nil- 810;; 0.2 g 23 SnQL 0.15 A Very good. smooth ,4 24 s cL, 0.10 Grainy 25 SnCL, 0.15 A Good, though not as good as Ex. 23. 26 FeCll fiHgO 0.15 A Good,thou h not as good as Ex. 23. 27 Hydrochloric acid B Adj. pH ofa uminum slurr to 7.0;

I broke with first addition otblay emulsion 28 Hydrochloric acid B d pl-l ofaluminum slurr to 6.

I broke with first addition 0 clay emulsion 29 Barium chlorlde hydrate 0.15 B Grainy-doughy; continued mixing gave smooth pr o duct EXAMPLE 30 brushed.

75 parts of a clay emulsion having the formula set EXAMPLE 32 forth in Table VII above was combined with 15 parts of Hydro Paste 830, 9.9 parts of water and 0.11 part of barium chloride hydrate using Method A as outlined above. The base composition obtained was heavy, thick, and gummy. 0.05 weight percent barium chloride hy-j drate and 9.0 weight percent water were added with mixing and a thin but smooth brushing composition resulted.

The same base composition was again prepared using This example shows the importance of the ratio of clay emulsion solids to aluminum metal content.

Various aluminum-clay emulsion compositions were formed using a clay emulsion having the composition disclosed in Table IV footnote 1, and varying quantities of Hydro Paste 830, barium chloride hydrate, and water. The quantities of the various constituents, the mixing method, and the results after four months of weath- Method B as outlined above. The result was a thin and ering are shown in Table IX.

TABLE IX ALUMINUM CLAY EMULSlONS HAVING VARYING ALUMINUM PIGMENT CONTENT Material: Parts by Wt. A B C D E Clay Emulsion 90 80 80 75 Hydro Paste 830 5 1(1 12.5 15 11) Barium Chloride Hydrate 0.11 5 0.1125 0.1125 0.1125 0.1125 Water 5 10 l0 l0 l0 Mixing Method A A A A A Uniformity & Texture Smooth Smooth Smooth Smooth Smooth Clay Emulsion Solids: 10.821 4.8:1 3.8:1 3:1 2.111

Aluminum Metal Ratio lnitial Color Dull. dark grey Grey coloration Bright Bright Bright Condition After 4 Months Complete loss Complete loss Some Bright Bright of color of color darkening Outdoor Weathering As will be evident to those skilled in the art, various modifications of this invention can be made or followed, in the light of the foregoing disclosure and discussion, Without departing from the spirit or the scope of the disclosure or from the scope of the following claims.

I claim:

1. A coating composition consisting essentially of l about 750 parts by weight of a clay base asphalt emulsion having a non-volatile residue of from 30 to 55 percent weight and a clay to asphalt ratio of from about 0.05O.40:l, wherein said asphalt has a penetration of O to about 250 at 77F., a softening point in the range of from about 80 to about 300F., and a mean particle size of from 4 to about 100 microns; (2) from about 50 to about 250 parts by weight of aluminum paste, the aluminum of said aluminum paste having been treated with an inhibitor to prevent reaction of the aluminum with water; (3) from about 50 to about 150 parts by weight mica; (4) from zero to about 2.5 parts by weight of a mixing stability additive; (5) from zero to about 250 parts by weight additional water; and (6) from zero to about 5 parts by weight sodium citrate hydrate with the proviso that the ratio of clay emulsion solids from said clay base asphalt emulsion to aluminum metal from said aluminum paste is in the range of from 1.5-8.0: l.

2. Claim 1, wherein said aluminum paste in present in an amount of from about 100 to 200 parts by weight, said mixing stability additive is present in an amount of from about 0.5 to about 2.0 parts by weight, said additional water is present in an amount of from about 150 to about 250 parts by weight, said sodium citrate hydrate is present in an amount of from about 0.5 to about 1.5 parts by weight.

3. Claim 2, wherein (1) said clay base asphalt emulsion has a non-volatile residue of from 38 to 47 percent weight, (2) a clay to asphalt ratio of from about 0.05-0.10z1, (3) the clay in said clay asphalt is bentonite clay, (4) said clay base asphalt has present from about 0 to about 0.4 part by weight of metasilicic acid, (5) from about 0 to about 1.0 part by weight ferric chloride hydrate, (6) said mixing stability additive is barium chloride hydrate, and (7) said sodium citrate hydrate is present in an amount from about 0.5 to about 1.0 part by weight.

4. Claim 3, wherein said aluminum paste is present in an amount of from about 125 to about 175 parts by weight, said barium chloride hydrate is present in an amount of from about 1 to about 1.5 parts by weight, and said mica is present in an amount of from about to parts by weight.

5. Claim 4, wherein said asphalt has a penetration in a range of from about 40 to 120 and a softening point in a range of from about 100 to about and the ratio of said clay emulsion solids to said aluminum metal is in a range of about 2.1-4.2:1.

6. Claim 5, wherein said aluminum paste is present and has about parts by weight and said mica is present in an amount of about 100 parts by weight and is of 100 mesh grade. 

1. A COATING COMPOSITION CONSISTING ESSENTIALLY OF (1) ABOUT 750 PARTS BY WEIGHT OF A CLAY BASE ASPHALT EMULSION HAVING A NON-VOLATILE RESIDUE OF FROM 30 TO 55 PERCENT WEIGHT AND A CLAY TO ASPHALT RATIO OF FROM ABOUT 0.05-0.40:1, WHEREIN SAID ASPHALT HAS A PENETRATION OF 0 TO ABOUT 250 AT 77*F., A SOFTENING POINT IN THE RANGE OF FROM ABOUT 80* TO ABOUT 300*F., AND A MEAN PARTICLE SIZE OF FROM 4 TO ABOUT 100 MICRONS; (2) FROM ABOUT 50 TO ABOUT 250 PARTS BY WEIGHT OF ALUMINUM PASTE, THE ALUMINUM OF SAID ALUMINUM PASTE HAVING BEEN TREATED WITH AN INHIBITOR TO PREVENT REACTION OF THE ALUMINUM WITH WATER; (3) FROM ABOUT 50 TO ABOUT 150 PARTS BY WEIGHT MICA; (4) FROM ZERO TO ABOUT 2.5 PARTS BY WEIGHT OF A MIXING STABILITY ADDITIVE; (5) FROM ZERO TO ABOUT 250 PARTS BY WEIGHT ADDITIONAL WATER; AND (6) FROM ZERO TO ABOUT 5 PARTS BY WEIGHT SODIUM CITRATE HYDRATE WITH THE PROVISO THAT THE RATIO OF CLAY EMULSION SOLIDS FROM SAID CLAY BASE ASPHALT EMULSION TO ALUMINUM METAL FROM SAID ALUMINUM PASTE IS IN THE RANGE OF FROM 1.5-8.0:1.
 2. Claim 1, wherein said aluminum paste in present in an amount of from about 100 to 200 parts by weight, said mixing stability additive is present in an amount of from about 0.5 to about 2.0 parts by weight, said additional water is present in an amount of from about 150 to about 250 parts by weight, said sodium citrate hydrate is present in an amount of from about 0.5 to about 1.5 parts by weight.
 3. Claim 2, wherein (1) said clay base asphalt emulsion has a non-volatile residue of from 38 to 47 percent weight, (2) a clay to asphalt ratio of from about 0.05-0.10:1, (3) the clay in said clay asphalt is bentonite clay, (4) said clay base asphalt has present from about 0 to about 0.4 part by weight of metasilicic acid, (5) from about 0 to about 1.0 part by weight ferric chloride hydrate, (6) said mixing stability additive is barium chloride hydrate, and (7) said sodium citrate hydrate is present in an amount from about 0.5 to about 1.0 part by weight.
 4. Claim 3, wherein said aluminum paste is present in an amount of from about 125 to about 175 parts by weight, said barium chloride hydrate is present in an amount of from about 1 to about 1.5 parts by weight, and said mica is present in an amount of from about 75 to 125 parts by weight.
 5. Claim 4, wherein said asphalt has a penetration in a range of from about 40 to 120 and a softening point in a range of from about 100 to about 140 and the ratio of said clay emulsion solids to said aluminum metal is in a range of about 2.1- 4.2:1.
 6. Claim 5, wherein said aluminum paste is present and has about 150 parts by weight and said mica is present in an amount of about 100 parts by weight and is of 100 mesh grade. 